UK Health Secretary Matt Hancock has warned Britons to reduce their social contacts amid the emergence of a new strain of the coronavirus that he said "was out of control".
The secretary told Sky News the government didn't want to make the U-turn and introduce tougher measures, but it was their duty to act.
"The new strain was out of control. We had to get it under control", Hancock told Sky's Sophy Ridge.
Mr Hancock went on to say that everyone in the newly-introduced Tier 4 zone must act as if they are already infected with the virus and called on the population to stay home.
The secretary also slammed those Londoners who tried to flee the capital before the new restrictions came into force.
"This was clearly totally irresponsible behaviour, and the Chief Medical Officer [Chris Whitty] was absolutely clear that people should unpack their bags if they have them packed", Mr Hancock said. "I think that it's relatively small numbers and the vast majority of people in the pandemic have followed the rules and played their part. It is more important than ever that people are responsible, not only stick to the rules but within the rules restrict social contact as much as is possible because this is deadly serious".
Tougher Restrictions Amid New Coronavirus Mutation
Despite promises not to ramp up restrictions in the UK during the Christmas season, Prime Minister Boris Johnson on Saturday announced that London as well as parts of eastern and southeastern England will fall under a set of stricter Tier 4 restrictions which virtually equals a lockdown.
Under the new measures, non-essential businesses will be closed and people will be required to stay at home unless they have to go out for essential shopping, for work that can't be performed remotely, for education, or for exercise.
The decision was taken in response to the discovery of a new coronavirus strain in England that is said to be transmitting at a faster pace that the earlier coronavirus strain.
Following the discovery and the announcement of new restrictions, Scotland and Wales also moved to intensify their coronavirus-related limitations.